19. In a gravimetric determination of nickel using dimethylglyoxime (DMG), a student performed three replicate trials. In each trial, the student weighed the nickel-DMG precipitate before it had reached a constant mass (i.e., the precipitate was still slightly damp with residual solvent). Which of the following statements best describes this error? (A) It is a random error that can be minimized by increasing the number of replicate measurements. (B) It is a systematic error that results in a positive bias, leading to a consistently higher calculated nickel content. (C) It is an indeterminate error that primarily affects the precision of the data set rather than its accuracy. (D) It is a systematic error that results in a negative bias, leading to a consistently lower calculated nickel content. (E) It is a random error caused by the inherent fluctuations in the ambient humidity of the laboratory.